This invention relates to Group 4 metal complexes containing an aryl substituted cyclopentadienyl ligand and to polymerization catalysts derived from such complexes that are particularly suitable for use in a polymerization process for preparing homopolymers and copolymers of olefins or diolefins, including copolymers comprising two or more olefins or diolefins such as copolymers comprising a monovinyl aromatic monomer and ethylene.
Constrained geometry metal complexes and methods for their preparation are disclosed in U.S. Pat. No. 5,703,187. This publication also teaches the preparation of certain novel copolymers of ethylene and a hindered vinyl monomer, including monovinyl aromatic monomers, having a pseudo-random incorporation of the hindered vinyl monomer therein. Additional teachings of constrained geometry catalysts may be found in U.S. Pat. Nos. 5,321,106, 5,721,185, 5,374,696, 5,470,993, 5,541,349, and 5,486,632, WO97/15583, WO97/19463.
In Table 1 of U.S. Pat. No. 5,723,560 and related patents, tetraphenylcyclopentadienyl-, 3,4-diphenylcyclopentadienyl-, and 2,5-diphenylcyclopentadienyl-ligands are listed. 2- and/or 3-substituted indenyl metal complexes are disclosed in U.S. Pat. No. 6,015,868. 3-Aryl-substituted indenyl metal complexes are disclosed in U.S. Pat. No. 5,866,704. Certain highly active, polyaromatic, metal complexes, especially derivatives of s-indacenyl- and cyclopentaphenanthrenyl-ligand groups are disclosed in U.S. Pat. No. 5,965,756 and U.S. Ser. No. 09/122,958, filed Jul. 27, 1998, (WO99/14221, published Mar. 25, 1999) respectively. Despite the advance in the art occasioned by the foregoing metal complexes, improved metal complexes that are capable of producing high styrene content ethylene/styrene interpolymers (ESI) and that are economical to prepare are continually desired. Accordingly, it would be desirable if there were provided metal complexes having acceptable catalytic properties that are also economical to produce.